Traditional probe card analyzers measure probe planarity by electrical means, and generally measure probe alignment by optical means. Electrical planarity measurements are typically made by slowly bringing a conductive contact surface into contact with the probes on a probe card. In that regard, the conductive contact surface is moved toward the probe card; the conductive surface first makes contact with the probe that extends furthest from the probe card surface (the “lowest” probe), and finally makes contact with the probe that extends least from the probe card surface (the “highest” probe). The process of moving the conductive contact surface from first to last contact point and beyond is generally referred to in the art as “overtravel,” since the first probe to make contact with the conductive contact surface is loaded beyond the point of first contact.
Some conventional probe card technologies implement probes having limited free vertical travel; in the “free-hanging” state, probes are not electrically connected to the probe card. Using traditional electrical planarity measurement technology, it is possible to overtravel the probes into a conductive contact surface and measure the overtravel associated with first electrical continuity. Currently implemented systems and methods are deficient, however, in that traditional methodologies do not enable accurate measurement of the range of free, electrically insulated, vertical motion, also known as “float.”